ML18051A921
| ML18051A921 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 06/07/1984 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML18051A920 | List: |
| References | |
| NUDOCS 8406130108 | |
| Download: ML18051A921 (4) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 82 TO PROVISIONAL OPERATING LICENSE NO. DPR-20 CONSUMERS POWER COMPANY
1.0 INTRODUCTION
DOCKET NO. 50-255 PALISADES PLANT By* letter dated September 29, 1983, Consumers Power Company (the licensee) proposed changes to the basis for the thermal margin/low pressure trip setting in the Pa~isades Technical Specifications by including the acceptance criterion and results of a reanalysis of the control rod withdrawal transient
.that takes into account the response time of the temperature detectors providing input to these safety system instruments.
This change would. also be reflected in the basis for the limit on linear heat rate.
At the request of the NRC staff, by letter dated November 1, 1983, Consumers Power Company submitted the Exxon Nuclear Company Report, XN-NF-709, "Justification of XNB Correlation for Palisades," May 1983, which was referenced in the September 29, 1983 application.
By letter dated May 11, 1984, the licensee provided additional clarifying information in response to the NRC staff's request for additional information dated May 3, 1984.
A Notice of Consideration of Issuance *of Amendment to License and Proposed No Significant Hazards Consideration Determination and Opportunity for Hearing related to the requested action was*.published in the Federal Register on November 22,, 1983 (48 FR 52811).
A request for hearing and public comments were not received.
- 2. 0 D'I SCUSS ION
.In a Licensee Event Report (LER) 83-20 submitted on April 5, 1983, Consumers Power Company reported they had discovered that the safety analyses contained in XN-NF-77-18, "Plant Transient Analyses of the Palisades Reactor for Operation at 2530 MWt" did not account for the response times of the resistance temperature detectors (RTDs) in the primary coolant system.
The..
hot and cold leg temperature RTD measurements are used in the thennal.
margin/low pressure (TM/LP) trip function for termination of rod withdrawal transients.
- The proposed change in the basis of technical specification 2.3 reflects the reanalysis of rod withdrawal transient for the Palisades reactor as described in XN-NF-83-57 Rod Withdrawal Transient Reanalysis for the Palisades Reactor."
The reanalysis used the UFEB82 version of the PTSPWR2 code (Ref. 1) including a pressurizer model which calculates the pressure increase in the pressurizer during rod withdrawal transients.
The effect of the RTD response time on the
<64 6J~/~0/(}g' p
TM/LP trip was included and the coolant flow update and the ENC XNB correlation to calculate DNB were used.
The radial peaking values were held constant instead of decreasing as the reactor power increased during the rod withdrawal.
The current Palisades Technical Specfication part power.""'peakil'.'lg limits were used for the analysis.
The following control rod withdrawal transients were analyzed:
(1) transients initiated from 102% of rated power at reactivity addition rates bounding the possible range.
(2) transients initiated from 52% of rated power at reactivity addition rates bounding the possible range.
Se.§linnd*ng of cycle, (BOC), mid-cycle (MC) and end of cycle (EOC) kinetics parameters were used in the analysis.
- 3. 0. EVALUA.T;TON Analysis of the rod withdrawal transient for the Palisades Reactor using the* previously used methodology and RTD delay times produced results that did not meet DNB limits. The reanalysis was undertaken using the UFEB82 version of the PTSPWR 2 Code (Ref. 1). This Code and methodology is under staff review which has progressed sufficiently that we have reasonable assurance that the results for rod withdrawal events will not be significantly altered by completion of our review. to this safety eval~ation is the NRC staff's evaluation of the ENC XNB correlation for Palisades (R~f. 2).
The staff finds that the XNB correlation is acceptable for*
application to Palisades with a minimum DNBR limit of 1.17.
Therefor~~
the staff concludes that it is acceptable to use the UFEB82 version of the PTSPWR 2 code and the XNB correlation for the Palisades reanalysis.
The previous analysis had allowed radial peaking values to increase as reactor power increased.
For the reanalysis, the more conservative approach, holding of the radial peaking values constant was used.
Since the RTD time constant was given as 7+/-2 seconds, the values used in the analysis were 9 seconds for the hot leg and 5 seconds for the cold leg in order to be conservative.
Three sets of kinetic parameters were used.
(1) beginning of cycle (BOC) minimum feedback (2) end of cycle (EOC) maximum feedback (3) mid-cycle Except for the EOC doppler coefficient, parameters used for BOC and EOC are identical to those previously used and are expected to bound values for future cycles.
The hot zero power EOC doppler coefficient was made *more negative by 20% in order to ensure bounding the feedback effects.
An analysis using mid-cycle parameters had not been performed previously.
- The conservative value of l.5%A(-' for maximum rod worth withdrawn was used for the BOC and EOC cases. Thii corresponds to the combined rod worth of banks 3 and 4, while the power dependent insertion limits (PDILs) for banks 3 and 4 allow only 20% and 80% insertion at 50% power.
For the MC casesr;' the maximum rod worth withdrawn was 1%~(' which is more reactivity than the PDILs allow to be inserted.
The minimum DNBR condition for all transients considered occurred for the mid-cycle case ~nitiated from 52% power for a reactivity addition rate of 1 ess than 3xl0-a e /second.
The minimum DNBR was 1.40 compared to the XNB DNBR limit of 1.17.
All BOC, EOC and MC cases initiated from 52% rated power with high or intermediate reactivity addition rates terminated on the over power neutron flux trip on high pressure trip. The BOC kinetics and low reactivity addition rate transients also trip on the high pressure trip.
For the EOC kinetics and low reactivity addition rate transient, no reactor trip occurred.
For the MC and low reactivity addition rate transients, the transients trip on*the thermal margin/low pressure trip (TM/LP).
The rod withdrawal transients from 102% power was also analysed for BOC, EOC and MC kinetics.
No limits were glaced on ~ank worths.
The range of reactivity addition rates was l.OxlO-to 3xl0- 4~
- The transients were all terminated by the high pressure trip, the TM/LP trip or the nuclear flux trip in all cases.
The lowest value of MDNBR was greater than 1.7.
. 4.0
- CONCLUSIONS
- rhe reanalysis of the rod withdrawal transients indicates that the use of the new PTSPWR 2 model, the XNB correlation and the coolant flow update more than compensate for the DNBR reducing effects of the RTD response time and the more conservative assumptions regarding part power radial peaking factors which were used in this analysis.
Based on our review of the report XN-NF-83-57 11Rod Withdrawal Transient Reanalysis for the Palisades Reactor," we agree with the licensee's conclusion that no fuel rod in the Palisades core will experience DNB during an un-controlled rod bank withdrawal transient.
Therefore, we find the proposed change in the basis of technical specification 2.3 to be acceptable.
5.0 ENVIRONMENTAL CONSIDERATION
The staff has determined that the amendment does not authorize a change in effluent types or total amounts nor an increase in power level and will not result in any significant environmental impact.
Having made this detennination, the staff has further concluded that the amendment involves an action which is insignificant from the standpoint of environmental impact and, pursuant to 10 CFR §51.5(d)(4), that an environmental impact statement or negative declaration and environmental impact appraisal need not be prepared in connection with the issuance of this amendment.
- 6. 0 CONCLUSION The staff has concluded, based on the considerations discussed above, that:
(1) there is reasonable as~urance that the health and safety of the public will not be endangered by operation in the proposed manner; and (2) such activities will be conducted in compliance with the Commission's regu-lations and the issuance of this amendment will not be inimical to the common defense.and security or to the health and safety of the public *
. 7.0 ACKNOWLEDGEMENT M. Chatterton prepared this evaluation.
Y. Hsii prepared the evaluation for the "Justification of XNB Correlation for Palisades," (Enclosure 1).
Dated: June 7, 1984
8.0 REFERENCES
c
- 1. Description of the "Exxon Nuclear Plant Transient Simulation Mode for Pressurized Water Reactors," (PTS-PWR), XN-75-5, Revision 2, August 1983.
- 2.
Macduff, R. B., "Justification of XNB Correlation for Palisades,"
XN-NF-709, Rev. 0, May 12, 1983.